My approach to writing is also informed by my fascination with history, or rather with our ongoing dialog with the past, where we continuously ask new questions about where we have been and receive new answers that have a bearing on where we go next. The preference for the diachronic over the synchronic also informs this introductory chapter, whose aim is to examine why, until recently, bilingualism played no role in discussions of language and thought and to understand what brought about the change. Yet, despite my love of history, I am not a historian of science – readers interested in the history of ideas about language diversity and thought should consult Allan (2007), Joseph (2002), Koerner (2002), Lucy (1992a), and Leavitt (2011). My own goal is to draw on these and other sources to discuss two lesser-known aspects of the history of what we know as the Sapir-Whorf hypothesis (SWH). To explain what happened to Humboldt’s idea of second-language (L2) learning as a way to transcend the boundaries of the first language (L1), I will depart from the traditional preoccupation of English-language academia with its own history and compare the treatment of Humboldt’s ideas in the US with that in Western Europe, Russia and the USSR. Then I will consider the invention of the SWH tradition in the US and ask how likely is it that Humboldt, Sapir, and Whorf, all of them multilingual and fascinated by language learning and change, believed that language determines thought? And if they did not, who did?